Humans Need Diverse Nutrients from Food Supply


  • Macro-nutrients: Carbohydrates, proteins & fats
    • carbohydrates & fats provide energy
    • proteins used as building blocks


  • Micro-nutrients: vitamins and minerals


  • When water removed from plants, mass is just macro-nutrients
    • foraging → agriculture → population ↑


  • Health advocates & advertisers promote diets based on these requirements
    • plants can satisfy most of these resource needs

Complex Carbohydrates from Plants

  • Commonly grouped into sugars and starches
    • mono-, di- & polysaccharides (# of sugar units)


  • Glucose & fructose (mono-) broken down in cellular respiration
    • corn syrup = high fructose
    • fructose common in fruit


  • Sucrose (di-) commonly found in table sugar
    • sugarcane and sugar beet


  • Starches (poly-) are main storage form in plants
    • seeds, fruits, tubers
    • major staple crops and underground crops

Fiber in the Human Diet



  • Fiber, a polysaccharides, is largely not digestible
    • derived from plant sources


  • Cellulose, lignin, pectin are components of cell walls
    • humans lack enzymes to break them down


  • Bacteria in intestines ferment soluble fibers!
    • stabilizes blood glucose
    • reduce cholesterol
    • reduces cancer risks

Plant-Based Proteins

  • 20 types of amino acids assembled into proteins
    • regulate a variety of body functions
    • proteins broken down by enzymes and transported through blood


  • Dietary proteins need to provide 9 of 20 amino acids
    • essential amino acids (9) not created or stored


  • Plant-based proteins are ‘incomplete’
    • do not contain all 9
    • varied plant diet needed


  • Traditional people of Mexico eat corn and beans

Gluten and Celiac Disease

Fats and Cholesterol from Plants


  • Some fats (lipids) are necessary in human diets
    • vital functions and heart health


  • Food lipids are mostly fats and oils


  • Human body cannot synthesis all fatty acids
    • linoleic, linolenic & arachidonic acids
    • all available in vegetable oils
    • 1 tsp of corn oil supply each


  • Vegetable oils are mostly unsaturated fats
    • olive, peanut, corn, soybean, etc,
    • unsaturated fats generally considered healthier

Micro-Nutrients from Plants



  • Vitamins (organic) play a role as co-enzymes
    • required for enzyme function


  • Vitamin A (vision pigments) from yellow, orange and dark green vegetables and fruits
    • beta-carotene


  • Vitamin C (collagen synthesis)
    • not produced or stored in body
    • fruits and vegetables

Micro-Nutrients from Plants


  • Minerals (inorganic) components of complex molecules
    • at least 18 minerals needed


  • Iron deficiency is common in women and children
    • only 10% of dietary iron absorbed
    • Leafy greens, grains, legumes and dried fruits


  • Iron from animal = heme; from plants = non-heme
    • heme gives blood its red color
    • some plants, like legumes, contain heme.

Plant-Based Diets




  • Vegetarian diets are shown to provide healthy benefits
    • fewer chronic diseases
    • blood cholesterol tracks animals fats
    • high fiber reduces diabetes risk


  • Plant-based diets must be aware of deficiencies
    • iron, Vitamin B & D, calcium
    • complementary plants for amino acids

The Staple Crops (Wheat, Maize & Rice)

Grass Family Most Important to Humans

  • Edible grains of cultivated grasses basic food of human civilization
    • wheat, core, rice
    • barely, oats, millet & rye


  • Sugar cane, a grass, world largest crop product
    • 26 million hectares in 90 countries


  • Dry fruits from the grass family are ‘grains’
    • seed is mostly endosperm = starch
    • refined into white flour, corn starch & white rice
    • fruit wall + seed coat = bran fiber


  • Wheat, Maize & Rice (refined + whole) provide 50% of human calories consumed

Wheat: The Staff of Life

  • Wheat ‘spikes’ are densely packed with grains
    • primarily grown in cool temperature zones
    • wild species found in Fertile Crescent


  • Einkorn wheat one of first cultivated species
    • domesticate from is ‘non-shattering’
    • hybridized with ‘goat grass’ to create ‘emmer wheat’
    • ‘emmer wheat’ crossed with another ‘goat grass’
    • diploid → tetraploid → hexaploid


  • Currently 1,000s of wheat cultivars
    • tolerance to climate
    • amount of gluten
    • protein content in endosperm

Corn: Indian Maize


  • Summer annual, moderate temp and rain
    • now: breed for diverse environments
    • requires nutrient-rich soil
    • today: hybrid corn w/ many large kernels


  • Unknown to arriving Europeans
    • most types cultivated by Native Americas
    • poorly adapted for natural environment (husks)


  • ‘Popcorn’ one of the most primitive varieties
    • hard kernels, ‘hard’ starch around ‘soft’ starch
    • burst and swell when heated
    • avoids processing

Rice: Food for Billions


  • Rice feeds more than any other crop

    • 2 billion people

    • 1,000’s of varieties


  • Originated from wild ancestor in flooded tropical lowlands
    • current: breed to grow any where


  • Large annual grass with air chambers in stems
    • air diffusion: stomata → roots


  • Rice mostly cultivated into flooded fields
    • aquatic fern, Azolla, provides nitrogen
    • fields drained to harvest